AutoCodes – Nissan – P0420 2008 Nissan Pathfinder

P0420 2008 Nissan Pathfinder Code - Catalyst System Efficiency Below Threshold Bank 1

Quick Answer

The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor). Common causes include Faulty Three-way Catalyst Converter Bank 1, Exhaust Tube, Intake Air Leaks. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0420 2008 Nissan Pathfinder indicates Catalyst System Efficiency Below Threshold Bank 1.
Common causes: Common causes include Faulty Three-way Catalyst Converter Bank 1, Exhaust Tube, Intake Air Leaks.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 17,374

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 20, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0420 2008 Nissan Pathfinder Description

The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor).
A three way catalyst converter (Manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase.
When the frequency ratio of heated oxygen sensors 1 and 2 approaches a specified limit value, the three way catalyst malfunction is diagnosed.

OBDII Code P0420 2008 Nissan Pathfinder - Catalyst System Efficiency Below Threshold Bank 1 - AutoCodes.com — P0420 2008 Nissan Pathfinder Code - Catalyst System Efficiency Below Threshold Bank 1

What does this mean?

What are the Possible Causes of the DTC P0420 2008 Nissan Pathfinder?

Faulty Three-way Catalyst Converter Bank 1
Exhaust Tube
Intake Air Leaks
Faulty Oxygen (O2) Sensor
Faulty Fuel injector(s)
Leaking Fuel Injector (s)
Faulty Spark plugs
Improper Ignition Timing
Faulty Engine Control Module (ECM)
Dirty Air Filter

How to Fix the DTC P0420 2008 Nissan Pathfinder?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0420 2008 Nissan Pathfinder code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0420 2008 Nissan Pathfinder code?

Need more information on how to fix the P0420 2008 Nissan Pathfinder code? Get Access to Factory Service Manuals

Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0420 2008 Nissan Pathfinder Code

1. What are the common symptoms of OBDII code P0420 in a 2008 Nissan Pathfinder?

The common symptoms include decreased fuel efficiency, rough idling, and the illumination of the check engine light.

2. What does the OBDII code P0420 on a 2008 Nissan Pathfinder indicate?

The code P0420 means that the catalyst system efficiency on Bank 1 is below the threshold.

3. What are the possible causes of OBDII code P0420 in a 2008 Nissan Pathfinder?

Potential causes include a faulty catalytic converter, oxygen sensor issues, exhaust leaks, or engine misfires.

4. Can I continue driving my 2008 Nissan Pathfinder with the P0420 code?

It is not recommended to drive for an extended period with the P0420 code illuminated, as it may lead to further engine damage.

5. How can I diagnose and repair the OBDII code P0420 in my 2008 Nissan Pathfinder?

Diagnosis involves checking the catalytic converter, oxygen sensors, and exhaust system for issues. Repair may involve replacing the catalytic converter, oxygen sensors, or addressing exhaust leaks.

6. Will resetting the OBDII code P0420 in my 2008 Nissan Pathfinder fix the issue?

Resetting the code may temporarily turn off the check engine light, but it will not address the underlying problem causing the code to trigger.

7. How much does it typically cost to repair the OBDII code P0420 on a 2008 Nissan Pathfinder?

The cost of repair can vary depending on the specific issue causing the code, but it may range from a few hundred to over a thousand dollars.

8. Can a DIY enthusiast fix the OBDII code P0420 in a 2008 Nissan Pathfinder?

While some may attempt DIY repairs, diagnosing and repairing the P0420 code often requires specialized tools and expertise, so it is recommended to seek professional help.

9. How often does the OBDII code P0420 occur in a 2008 Nissan Pathfinder?

The P0420 code can occur intermittently or persistently, depending on the severity and nature of the underlying issue.

10. Is there a way to prevent the recurrence of the OBDII code P0420 in my 2008 Nissan Pathfinder?

Regular maintenance, timely repairs of any related issues, and using high-quality fuel can help prevent the recurrence of the P0420 code in your vehicle.